How long does it take for a cylinder to break in

AKBill

AKBill

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AKBill
Changed my #1 cylinder 20 hours ago. I did a compression test this weekend and only got 54/80. Steel cylinder 0320 wide deck

I called the Tony who rebuilt it and he said to run it another 10 hours and recheck compression.

I would thing the rings would have seated by now. Tony told me the it could take up 100 hours to seat.

Comments please.
 
AKBill said:
Changed my #1 cylinder 20 hours ago. I did a compression test this weekend and only got 54/80. Steel cylinder 0320 wide deck

I called the Tony who rebuilt it and he said to run it another 10 hours and recheck compression.

I would thing the rings would have seated by now. Tony told me the it could take up 100 hours to seat.

Comments please.
Click to expand...

What finish did the overhauler finish the bore?

What's your oil consumption?

Where was the escaping air coming from?

Chrome rings?
 
Tom-D said:
What finish did the overhauler finish the bore?

What's your oil consumption?

Where was the escaping air coming from?

Chrome rings?
Click to expand...

Oil consumption about 1 quart in 15 hours.
Bypassing rings, can hear air out breather tube.
Don't know finish or rings.
 
It shouldn't take that long. How long is a new engine break in run? I'm a jet mechanic with quite a bit of automobile experience. When auto engines are being broken-in you should use non detergent/or break-in oil. That may be the issue.
 
Detergents prevent sludge buildup by keeping the contaminants in suspension. Since during break in you are wearing away the metal on the cylinder wall so you don't want that. With a single cylinder, cam an crank and all other cylinders already broken in it's not a big deal really.

20 hours is quite a bit of time. It depends on how you're running the engine, during break in you don't want to baby it. You also don't want to do a lot of ground running and heat buildup. Also depends on how the cylinder was prepared, type of rings and such. There are times when it doesn't work out if things aren't done right.
 
Sounds like something is wrong to me. I've always just flown them hard for two hours or so and the compression has always checked out good from there.
 
There is a good possibility the cylinder over heated and took the temper out of the rings.

Or

When he took the compression readings the end gap was aligned.
 
Silvaire said:
Detergents prevent sludge buildup by keeping the contaminants in suspension. Since during break in you are wearing away the metal on the cylinder wall so you don't want that. With a single cylinder, cam an crank and all other cylinders already broken in it's not a big deal really.
Click to expand...

No aviation oils include detergents. Most do use ashless dispersant. Old timers will use straight (no ashless dispersant) mineral oil for break-in. Nothing wrong with that. Per ECI I've used Phillips X/C (mineral oil with ashless dispersant) for break-in of my last engine and a couple of repaired cylinders in another engine. It works great. What you want to avoid like the plague at break-in is semi synthetic oils (Aeroshell 15-50 and Exxon Elite) and oil additives like Avblend and Camguard. Use a mineral oil and run it at high cylinder pressures to seat the rings. When in doubt, look up ECI's break-in instructions on their website. They offer good advice for the popular cylinder types (steel, nickel, chrome).

http://www.eci.aero/pdf/BreakInInstructions.pdf
 
Borescope the cylinder compression checks are next to worthless. See if it's glazed from heat or gouged/damaged. Maybe a valve isn't seating correctly?
 
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How much do the other cylinders and the rest of the engine get beat up when you're "breaking in" one cylinder?
 
luvflyin said:
How much do the other cylinders and the rest of the engine get beat up when you're "breaking in" one cylinder?
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They don't. Not "babying" it is not the same as " beating it up"
 
A common mistake is to baby it. That new cylinder and rings needs heat and pressure to seat those rings, and that means high power settings. 75% in cruise. At some altitudes, that will mean full throttle.
 
AKBill said:
Changed my #1 cylinder 20 hours ago. I did a compression test this weekend and only got 54/80. Steel cylinder 0320 wide deck

I called the Tony who rebuilt it and he said to run it another 10 hours and recheck compression.

I would thing the rings would have seated by now. Tony told me the it could take up 100 hours to seat.

Comments please.
Click to expand...

Fly it to Skagway and back over the ice. That'll do it. :goofy:
 
jesse said:
Sounds like something is wrong to me. I've always just flown them hard for two hours or so and the compression has always checked out good from there.
Click to expand...

I wish I would have done a check as you say after about 2 hours, I certainly did not baby it.

Tom-D said:
There is a good possibility the cylinder over heated and took the temper out of the rings.

Or

When he took the compression readings the end gap was aligned.
Click to expand...

Don't think I overheated it's the coolest running cylinder, several folks have suggested the end gaps are aligned.


Htaylor said:
Fly it to Skagway and back over the ice. That'll do it. :goofy:
Click to expand...
I like Skagway, tourist are all gone till next year, nice and quiet this time of year.
 
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